fix(core): Fix telemetry for concurrency control (n8n-io#9845)

Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>

packages/cli/src/concurrency/__tests__/concurrency-control.service.test.ts

@@ -1,6 +1,10 @@
 import { mock } from 'jest-mock-extended';
 import config from '@/config';
-import { ConcurrencyControlService } from '@/concurrency/concurrency-control.service';
+import {
+	CLOUD_TEMP_PRODUCTION_LIMIT,
+	CLOUD_TEMP_REPORTABLE_THRESHOLDS,
+	ConcurrencyControlService,
+} from '@/concurrency/concurrency-control.service';
 import type { Logger } from '@/Logger';
 import { InvalidConcurrencyLimitError } from '@/errors/invalid-concurrency-limit.error';
 import { ConcurrencyQueue } from '../concurrency-queue';
@@ -366,4 +370,91 @@ describe('ConcurrencyControlService', () => {
 			});
 		});
 	});
+
+	// ----------------------------------
+	//            telemetry
+	// ----------------------------------
+
+	describe('telemetry', () => {
+		describe('on cloud', () => {
+			test.each(CLOUD_TEMP_REPORTABLE_THRESHOLDS)(
+				'for capacity %d, should report temp cloud threshold if reached',
+				(threshold) => {
+					/**
+					 * Arrange
+					 */
+					config.set('executions.concurrency.productionLimit', CLOUD_TEMP_PRODUCTION_LIMIT);
+					config.set('deployment.type', 'cloud');
+					const service = new ConcurrencyControlService(logger, executionRepository, telemetry);
+
+					/**
+					 * Act
+					 */
+					// @ts-expect-error Private property
+					service.productionQueue.emit('concurrency-check', {
+						capacity: CLOUD_TEMP_PRODUCTION_LIMIT - threshold,
+					});
+
+					/**
+					 * Assert
+					 */
+					expect(telemetry.track).toHaveBeenCalledWith('User hit concurrency limit', { threshold });
+				},
+			);
+
+			test.each(CLOUD_TEMP_REPORTABLE_THRESHOLDS.map((t) => t - 1))(
+				'for capacity %d, should not report temp cloud threshold if not reached',
+				(threshold) => {
+					/**
+					 * Arrange
+					 */
+					config.set('executions.concurrency.productionLimit', CLOUD_TEMP_PRODUCTION_LIMIT);
+					config.set('deployment.type', 'cloud');
+					const service = new ConcurrencyControlService(logger, executionRepository, telemetry);
+
+					/**
+					 * Act
+					 */
+					// @ts-expect-error Private property
+					service.productionQueue.emit('concurrency-check', {
+						capacity: CLOUD_TEMP_PRODUCTION_LIMIT - threshold,
+					});
+
+					/**
+					 * Assert
+					 */
+					expect(telemetry.track).not.toHaveBeenCalledWith('User hit concurrency limit', {
+						threshold,
+					});
+				},
+			);
+
+			test.each(CLOUD_TEMP_REPORTABLE_THRESHOLDS.map((t) => t + 1))(
+				'for capacity %d, should not report temp cloud threshold if exceeded',
+				(threshold) => {
+					/**
+					 * Arrange
+					 */
+					config.set('executions.concurrency.productionLimit', CLOUD_TEMP_PRODUCTION_LIMIT);
+					config.set('deployment.type', 'cloud');
+					const service = new ConcurrencyControlService(logger, executionRepository, telemetry);
+
+					/**
+					 * Act
+					 */
+					// @ts-expect-error Private property
+					service.productionQueue.emit('concurrency-check', {
+						capacity: CLOUD_TEMP_PRODUCTION_LIMIT - threshold,
+					});
+
+					/**
+					 * Assert
+					 */
+					expect(telemetry.track).not.toHaveBeenCalledWith('User hit concurrency limit', {
+						threshold,
+					});
+				},
+			);
+		});
+	});
 });

packages/cli/src/concurrency/__tests__/concurrency-queue.test.ts

@@ -1,3 +1,4 @@
+import { sleep } from 'n8n-workflow';
 import { ConcurrencyQueue } from '../concurrency-queue';
 
 describe('ConcurrencyQueue', () => {
@@ -10,12 +11,12 @@ describe('ConcurrencyQueue', () => {
 		const state: Record<string, 'started' | 'finished'> = {};
 
 		// eslint-disable-next-line @typescript-eslint/promise-function-async
-		const sleep = jest.fn(() => new Promise((resolve) => setTimeout(resolve, 500)));
+		const sleepSpy = jest.fn(() => sleep(500));
 
 		const testFn = async (item: { executionId: string }) => {
 			await queue.enqueue(item.executionId);
 			state[item.executionId] = 'started';
-			await sleep();
+			await sleepSpy();
 			queue.dequeue();
 			state[item.executionId] = 'finished';
 		};
@@ -29,33 +30,46 @@ describe('ConcurrencyQueue', () => {
 		]);
 
 		// At T+0 seconds this method hasn't yielded to the event-loop, so no `testFn` calls are made
-		expect(sleep).toHaveBeenCalledTimes(0);
+		expect(sleepSpy).toHaveBeenCalledTimes(0);
 		expect(state).toEqual({});
 
 		// At T+0.4 seconds the first `testFn` has been called, but hasn't resolved
 		await jest.advanceTimersByTimeAsync(400);
-		expect(sleep).toHaveBeenCalledTimes(1);
+		expect(sleepSpy).toHaveBeenCalledTimes(1);
 		expect(state).toEqual({ 1: 'started' });
 
 		// At T+0.5 seconds the first promise has resolved, and the second one has stared
 		await jest.advanceTimersByTimeAsync(100);
-		expect(sleep).toHaveBeenCalledTimes(2);
+		expect(sleepSpy).toHaveBeenCalledTimes(2);
 		expect(state).toEqual({ 1: 'finished', 2: 'started' });
 
 		// At T+1 seconds the first two promises have resolved, and the third one has stared
 		await jest.advanceTimersByTimeAsync(500);
-		expect(sleep).toHaveBeenCalledTimes(3);
+		expect(sleepSpy).toHaveBeenCalledTimes(3);
 		expect(state).toEqual({ 1: 'finished', 2: 'finished', 3: 'started' });
 
 		// If the fourth promise is removed, the fifth one is started in the next tick
 		queue.remove('4');
 		await jest.advanceTimersByTimeAsync(1);
-		expect(sleep).toHaveBeenCalledTimes(4);
+		expect(sleepSpy).toHaveBeenCalledTimes(4);
 		expect(state).toEqual({ 1: 'finished', 2: 'finished', 3: 'started', 5: 'started' });
 
 		// at T+5 seconds, all but the fourth promise should be resolved
 		await jest.advanceTimersByTimeAsync(4000);
-		expect(sleep).toHaveBeenCalledTimes(4);
+		expect(sleepSpy).toHaveBeenCalledTimes(4);
 		expect(state).toEqual({ 1: 'finished', 2: 'finished', 3: 'finished', 5: 'finished' });
 	});
+
+	it('should debounce emitting of the `concurrency-check` event', async () => {
+		const queue = new ConcurrencyQueue(10);
+		const emitSpy = jest.fn();
+		queue.on('concurrency-check', emitSpy);
+
+		// eslint-disable-next-line @typescript-eslint/promise-function-async
+		Array.from({ length: 10 }, (_, i) => i).forEach(() => queue.enqueue('1'));
+
+		expect(queue.currentCapacity).toBe(0);
+		await jest.advanceTimersByTimeAsync(1000);
+		expect(emitSpy).toHaveBeenCalledTimes(1);
+	});
 });

packages/cli/src/concurrency/concurrency-control.service.ts

@@ -9,6 +9,9 @@ import type { WorkflowExecuteMode as ExecutionMode } from 'n8n-workflow';
 import type { IExecutingWorkflowData } from '@/Interfaces';
 import { Telemetry } from '@/telemetry';
 
+export const CLOUD_TEMP_PRODUCTION_LIMIT = 999;
+export const CLOUD_TEMP_REPORTABLE_THRESHOLDS = [5, 10, 20, 50, 100, 200];
+
 @Service()
 export class ConcurrencyControlService {
 	private readonly isEnabled: boolean;
@@ -17,7 +20,9 @@ export class ConcurrencyControlService {
 
 	private readonly productionQueue: ConcurrencyQueue;
 
-	private readonly limitsToReport = [5, 10, 20, 50, 100, 200];
+	private readonly limitsToReport = CLOUD_TEMP_REPORTABLE_THRESHOLDS.map(
+		(t) => CLOUD_TEMP_PRODUCTION_LIMIT - t,
+	);
 
 	constructor(
 		private readonly logger: Logger,
@@ -46,19 +51,17 @@ export class ConcurrencyControlService {
 
 		this.isEnabled = true;
 
-		this.productionQueue.on(
-			'execution-throttled',
-			async ({ executionId, capacity }: { executionId: string; capacity: number }) => {
-				this.log('Execution throttled', { executionId });
-
-				/**
-				 * Temporary until base data for cloud plans is collected.
-				 */
-				if (this.shouldReport(capacity)) {
-					await this.telemetry.track('User hit concurrency limit', { threshold: capacity });
-				}
-			},
-		);
+		this.productionQueue.on('concurrency-check', ({ capacity }: { capacity: number }) => {
+			if (this.shouldReport(capacity)) {
+				void this.telemetry.track('User hit concurrency limit', {
+					threshold: CLOUD_TEMP_PRODUCTION_LIMIT - capacity,
+				});
+			}
+		});
+
+		this.productionQueue.on('execution-throttled', ({ executionId }: { executionId: string }) => {
+			this.log('Execution throttled', { executionId });
+		});
 
 		this.productionQueue.on('execution-released', async (executionId: string) => {
 			this.log('Execution released', { executionId });

packages/cli/src/concurrency/concurrency-queue.ts

@@ -1,5 +1,6 @@
 import { Service } from 'typedi';
 import { EventEmitter } from 'node:events';
+import debounce from 'lodash/debounce';
 
 @Service()
 export class ConcurrencyQueue extends EventEmitter {
@@ -15,14 +16,20 @@ export class ConcurrencyQueue extends EventEmitter {
 	async enqueue(executionId: string) {
 		this.capacity--;
 
+		this.debouncedEmit('concurrency-check', { capacity: this.capacity });
+
 		if (this.capacity < 0) {
-			this.emit('execution-throttled', { executionId, capacity: this.capacity });
+			this.emit('execution-throttled', { executionId });
 
 			// eslint-disable-next-line @typescript-eslint/return-await
 			return new Promise<void>((resolve) => this.queue.push({ executionId, resolve }));
 		}
 	}
 
+	get currentCapacity() {
+		return this.capacity;
+	}
+
 	dequeue() {
 		this.capacity++;
 
@@ -56,4 +63,9 @@ export class ConcurrencyQueue extends EventEmitter {
 
 		resolve();
 	}
+
+	private debouncedEmit = debounce(
+		(event: string, payload: object) => this.emit(event, payload),
+		300,
+	);
 }